(UPDATED: Monday 3/26, 11 a.m.) The very barren bottom of the Mariana Trench had a visitor Sunday night: filmmaker James Cameron. After years of preparation, Cameron descended 35,756 ft. (10,898 m) beneath the ocean’s surface in his 12-ton lime green submarine called Deepsea Challenger.

It was a mission filled with near constant danger. At 6.8 miles (11 km) deep, the trench allowed not a hint of sunlight from above, was just a few degrees above freezing temperature and put 8 tons of pressure per sq. in. on the filmmaker. That’s equivalent to three SUVs sitting on your toe, researchers have determined.

In fact, everything about Cameron’s dive was at a nearly incomprehensible scale. The trench is 120 times larger than the Grand Canyon and is more than a mile deeper than Mount Everest is tall.

The Titanic director’s solo journey to the ocean’s deepest point took nearly three hours. He departed at 5:15 a.m. Monday local time from a starting point 200 miles (320 km) southwest of the Pacific island of Guam. He touched down at 7:52 a.m. local time (5:52 p.m. E.T. Sunday), according to the National Geographic Society. His Twitter account reflected the incredible feat:

Only two men preceded him in the highly dangerous mission. U.S. Navy Lieutenant Don Walsh and Swiss oceanographer Jacques Piccard made the dive in 1960, spending only 20 minutes at the bottom. Worse yet, they could hardly see anything after their rough landing kicked up sand from the seafloor.

But Cameron planned a much longer stay. His 24-ft.-long (7 m long) custom-built “vertical torpedo” was armed with enough oxygen and personal resources for the exploratory mission that lasted three hours. The submarine was outfitted with so many lights and 3-D cameras that it’s been described as an underwater TV studio. And while Cameron might have been alone at such unfathomable depths, he plans to share his experience with the masses by releasing a documentary. He also attempted to collect rocks and soil samples to assist with scientific research, but there was a problem with his probe that prevented the system from grabbing anything. But Cameron seemed hardly worried about the minor problem, because, after all, he plans to return. “I see this as the beginning,” Cameron said in a Monday morning conference call. “It’s not a one-time deal and then moving on. This is the beginning of opening up this new frontier.”